Capesius, Alan writes:

... with further testing I have determined that the Zope server itself is not locking up, but rather requests to the database (MS SQL7 via ZODBCDA) seem to be queueing up. My memory tells me faintly that such an issue has already been discussed in the mailing lists (zope, zope-dev). When I remember right, ZODBCDA synchronizes all database requests --> searchable list archives...

Dieter